The explosive failure, which destroyed a rocket and spacecraft valued at more than $200 million, is a modest setback for commercial companies that took over missions to space after NASA ended its space shuttle program in 2011.

“Space flight is inherently risky,” Sen. Bill Nelson (D-Fla.), chairman of the Senate subcommittee on Science and Space, said in a statement. “As we push the frontiers of space, there will be setbacks. But our commercial space ventures will ultimately be successful.”

Following the explosion, the Orbital Sciences stock price dropped more than 16 percent Wednesday. The incident has also placed added scrutiny on SpaceX, a competing company that is similarly contracted with NASA to complete cargo missions to the ISS.

“Orbital has experienced adversity in the past, some of which was more difficult than this,” said Orbital chief executive David Thompson, who also noted that the Wallops Island launch pad didn’t suffer significant damage during the explosion.

The company is insured against the launch failure, Thompson said. At this point, Tuesday’s explosion could push back the launch of the next resupply mission, scheduled for early April, by at least three months. In the worst case, it could be up to a year, he said.

Thompson: likely will be days, not weeks, for investigators to determine most likely causes of failure; longer to zero in on exact cause.

The rocket’s flight-termination system, which is designed to detect flight anomalies, was engaged shortly after launch, causing it to self-destruct. It is unclear whether that system was triggered by the rocket’s automated on-board systems or by mission control, Orbital Sciences spokesman Barron Beneski said Wednesday.

“A malfunction was detected, the flight termination system was engaged,” Beneski said.

Despite the failure, astronauts aboard the ISS are in no danger of running out of supplies.

Water, oxygen & food are critical consumables. Should have lots for now. Next resupply launch is Russian, tomorrow, & @SpaceX in December.

A Russian resupply vehicle successfully docked with the ISS on Wednesday, about 15 hours after the Antares disaster at Wallops Island.

An unmanned Russian supply rocket blasted off from the Baikonur Cosmodrom in Kazakhstan Wednesday on a resupply mission to the International Space Station. The launch came one day after a private U.S. rocket exploded while attempting a similar mission. (Reuters)

“We will determine the root cause, and we will correct that, and we will come back and fly here at Wallops again — hopefully in the very near future,” Frank Culbertson, a former NASA astronaut who now serves as an executive vice president at Orbital Sciences, said at a news conference Tuesday night. “But we will do all the things that are necessary to make sure it is as safe as we can make it, and that we do solve the immediate problem of this particular mission.”

Culbertson said the investigation will include evaluating the debris around the site. He asked residents in the area to contact officials if they find pieces of the rocket on their property, or if they locate scraps that might wash ashore.

“We have reams and reams of data that comes down from the rocket during launch, and we will be analyzing that carefully to see if we can determine exactly the sequence of events, what went wrong, and then what we can do to fix it,” Culbertson said. “We also have video evidence that we’ll evaluating to help us with the investigation.”

That work began with an aerial survey of the launch pad area along the coast of Wallops Island; a team is searching for debris and evidence of hazardous materials, such as propellant or rocket motor fuel.

“Let’s find where the structures are, that will tell us a little bit and will instruct us on the nature of the angle of the flight and the blast,” Beneski said.

A NASA spokesperson said in an e-mail that while Orbital Sciences is leading the investigation, the agency hopes to have more information on the launch pad assessments by Wednesday afternoon.

Orbital Sciences, a private company based in Dulles, Va., had previously conducted resupply missions from Wallops Island. Shortly after the Tuesday explosion, the company called the event a “vehicle anomaly.” It intends to fulfill its obligation to NASA to restock the ISS, but that process could take some time, Beneski said.

“Certainly more than a few weeks. What we’re looking at probably measures in months,” he said. “Exactly how many months, we don’t know.”

Very sorry to see the Antares rocket launch failure. Spaceflight is hard. Very glad that no one was hurt. Now time to sort out why & effects

In Wednesday’s call with investors, Thompson said the failure of the Antares launch could speed up the development of a new propulsion system.

Orbital is already developing a second-generation version of the Antares rocket engine for NASA and is on track to test that in two years’ time, he said.

Stressing that it was still too early in the investigation to know whether the Aerojet Rocketdyne AJ-26 engines, which were used in the first stage of Tuesday’s launch, caused the explosion, Thompson said Orbital “may decide to accelerate this change if the AJ-26 is implicated in the failure.”

“We can certainly shorten that [two-year] interval but at this point, I don’t know by how much,” he said.

Elon Musk, CEO of SpaceX, called use of the rockets “the punchline to a joke.”

“It uses Russian rocket engines that were made in the ’60s,” Musk told Wired magazine in 2012. “I don’t mean their design is from the ’60s — I mean they start with engines that were literally made in the ’60s and, like, packed away in Siberia somewhere.”

In a tweet Tuesday night, Musk said he was “sorry” to hear about the launch failure. “I hope they recover soon,” he wrote.

Beneski said his company has successfully launched eight AJ-26 rockets — two on each of their four previous missions — without any problems.

“They are some of the most tested rockets in the history of rocketry,” Beneski said. “These two engines passed the tests and inspections that we put them through.”

“Again, to be clear, we don’t know if it was these engines that really caused the failure,” he added.

Marco Caceres, the director of space studies for the Teal Group, an aerospace industry analysis firm, predicted Wednesday that the launch failure would inevitably lead to “Monday morning quarterbacking” from “people within Congress and the space industry who continue to believe that NASA should continue to own, manage and operate its own launch vehicle instead of leasing launch services from private companies.”

But, Caceres said in an e-mail: “The reality is that catastrophic launch failures like the one we saw yesterday have little to do with whether it’s a private company managing things or NASA. NASA has had its share of horrendous failures — both in terms of launch vehicles and satellites. The idea that the government is inherently better suited for spaceflight is a myth.”

The Russian spacecraft that docked Wednesday carried food and other supplies, including fuel, according to the Associated Press. It had launched from Kazakhstan and arrived at the station in about six hours.